This invention relates to an improved latch for securing together two members and more particularly but not by way of limitation to a latch for securing together a pair of hinged cowlings surrounding an aircraft engine.
Prior to the subject invention a problem existed with some aircraft cowling latches in that maintenance personnel were required to use both hands when hooking up or unlocking the cowling latches. This is especially true with an overcenter hook type latch since this type of latch has an internal spring force acting against the latch handle and the latch hook, forcing the two apart usually toward an open direction thereby moving the hook away from the latch keeper. The latch keeper being attached to an opposing hinged cowling is usually an eye bolt, "U" bolt or standard bolt or a pin.
For latching a standard overcenter hook latch, the sequence of operation required the two hinged cowlings to be brought together and aligned by some means and then latched. The operator then grasps the latch handle with one hand and with the other hand moves the latch hook into a position near the keeper. He then rotates the handle toward the closed position while holding the hook until it engages the keeper. The operator continues rotating the handle to its fully closed position to complete the latching cycle. By rotating the handle to the closed position the hook is moved overcenter or past a centerline through the keeper and the bolt securing the handle to the cowling and thereby increasing the latching force to a present amount. A safety lock on the latch is automatically engaged upon closing and prevents the latch from inadvertently opening due to the relaxing of the forces between the cowling halves.
In unlatching the hook latch, the operator depresses the safety lock allowing the handle to rotate freely toward an open position. The free rotation of the handle gives the operator room to grasp the handle. The free rotation occurs after release of the safety lock but does not effect the hook-up forces. The handle is then rotated toward the open position which in turn moves the pivot of the hook overcenter releasing the latching forces. Further rotation causes the hook to be disengaged from the latch keeper. However, depending on the latch geometry, handle rotation and/or latch mounting position, the hook may or may not be free of the keeper. Therefore, the operator must use one hand to move the hook off of the keeper while the other hand moves the handle. The subject invention eliminates the above mentioned problem of the operator having to use both hands in securing or releasing the latch hook from the latch keeper.
Heretofore there have been various types of latches such as those described in U.S. Pat. No. 2,712,955 to Andrews, U.S. Pat. No. 2,894,777 to Hogan, U.S. Pat. No. 2,927,812 to Smith et al, U.S. Pat. No. 3,259,412 to Wheeler and U.S. Pat. No. 4,318,557 to Bourne et al. None of the latches described in the above mentioned patents particularly point out the unique structure and features of the improved latch and the advantages of this latch as described herein.